This invention is directed to the field of lubrication for pneumatic tools and particularly relates to providing for a reliable source of atomized lubricant into the compressed air line connected to pneumatic tools such as rock drills, hammers, motors or the like.
Providing a reliable and consistent supply of lubricant into a working air line serving pneumatic tools has been a problem for a number of reasons. Certain lubricants, for example, tend to collect along the sidewalls of the working air line when injected therein in a large droplet form or in a partially atomized form. In this situation a film of lubricant will progress down the inside walls of the air line but will tend to collect principally along one side of the line and this is believed due in part to gravitational forces as well as the attractiveness between the wall surface and the lubricant and the driving forces of the moving air. Overall this results in inefficient delivery of the lubricant to the working tool. Air lines operating in the range of 150 to 500 psig and frequently up to 1,500 psig and flow rates on the order of 1500 cubic feet per minute are commonly employed to power and drive drills and other air tools for mining operations. High volume flow rates up to 30,000 cfm are not rare. Other applications needing reliable air delivered lubrication are air powered rock hammers such as those employed in coal, copper or gold mines as well as pneumatic motors. Failure of the air powered tools in every instance causes substantial problems in the field, including down-time for repair or replacement of the equipment including its removal and replacement from the work site. The replacement cost of a pneumatic hammer is substantial and exceeds the cost of the inventive apparatus disclosed herein.
In the prior art, the Bardin U.S. Pat. No. 4,335,804 discloses structure for forming an oil mist through generation of a vortex with the objective of directing the oil tangential to the direction of air flow. The Shepard U.S. Pat. No. 2,172,092 employs flow control of lubricant from a pressurized lubricant holding compartment through a needle valve. The Lansky U.S. Pat. No. 3,720,290 discloses dispersing oil in a path concentric with the axis of flow through the use of a supersonic whistle which converts the liquid oil into a mist. The Slater U.S. Pat. No. 2,227,278 also discloses the problem of lubricating oil depositing along the sidewalls of a conduit carrying the compressed air but addresses the problem through employment of the structure substantially different from that disclosed herein. Furthermore, mechanical moving parts, springs, severe air line restrictions and exposed areas prone to becoming plugged by contaminant particles characterize the deficiencies of this prior art.